Electronics > Beginners
Motor+Circuit for a water generator
spec:
--- Quote from: t1d on October 29, 2018, 10:02:15 pm ---Great circuit, Spec!
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Thanks t1d, but it is pretty standard stuff.
--- Quote from: t1d on October 29, 2018, 10:02:15 pm ---
JuculianD, something to add to the circuit is a switch, to change over from charging the battery to using the battery.
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I'm intrigued by this change-over switch. Is that a safety requirement in the marine world?
I had imagined that, like with the case of a car alternator/battery system, that the generator would be connected permanently. :)
spec:
--- Quote from: JuculianD on October 30, 2018, 03:04:25 pm ---Wow, that was very much helpful information.
Thank you very much for your enthusiasm!
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No problem from me JuculianD :)
Regarding your technical questions about using motors as generators, just search the internet- there is a heap of information on the subject. One very popular motor is from a treadmill.
A typical car alternator will give you about 20V at up to 80 amps or so maximum, but car alternators are not very efficient, only about 50%. All the same there is no reason why you could not experiment with a car alternator as they have all the circuity to charge a battery already built in. Car alternators are also rugged and reliable.
About rectifying a three line output- yes you are on the right track. A three phase bridge rectifier would be required- just take a look at a car alternator schematic.
Another approach, is to use a motorcycle alternator- not the type that is integrated with the crankshaft output, but the type that are a separate unit, like the old DC generators. Once again, with the bike rectifier regulator you would have everything done for you. The advantage of a motorcycle alternator is that it is smaller and lighter than a car alternator.
You question about the output characteristics of a motor used as a generator has many aspects, that depend on the type of motor, motor rotational speed, and current loading. But, to a very rough approximation the out put voltage is proportional to rotational speed and inversely proportional to current load. To give an example, a motorcycle alternator for a 12V system will produce around 80v RMS off load.
JuculianD:
I definetely do want to use a brushless motor with 40mm width - 60Kv.
I will now do a PCB design with the diodes and also a charging controller if possible.
I am now going to take a look in the internet.
Thank you very much.
t1d:
--- Quote from: spec on October 30, 2018, 03:12:06 pm ---I'm intrigued by this change-over switch. Is that a safety requirement in the marine world?
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Well, my responses have been wide, in scope, because we still have not been informed about the boat, etc. As for being a requirement, it depends on the boat... But, it is always a safety concern. It may also be required by the boat insurance underwriter; it usually is, in the fine print...
Depending on the parts of the system (engine type, battery type, charger type, etc.,) the switch may be an operational requirement. For example, having the charging system tied to the starter of some types of outboards engines, at the moment you start the engine, can fry the outboard engine electrical components. We still need information about the boat, the engine, the intended sailing region, etc.
Have we been told, exactly, what the generator powering method will be? Wind, or hydro?
JuculianD
A major consideration, in choosing the generator, is the amount of torque that is needed, to turn the generator, throughout all the expected RPM ranges, of use, because, the torque needed changes. For example, I looked at building a floating generator, to ride in a small stream. It was going to be difficult, to turn the generator (of the size needed for the target voltage/amperage) with the water current that was available.
Take any spare motor, of the same type, as you intend to use, and try spinning it, by hand. It will be much more difficult, than you would think. If it is making any significant usable power, it is not going to freewheel.
Then, chuck the shaft, of the motor, into a drill motor. Secure the motor's body. Attach your multimeter leads. Spin the motor, varying the RPM. Observe the power, that you get. You will gain much insight, by this simple experiment.
You may not want to buy anything, until you have a complete design, for the entire system. I think that you have a long way to go... learning the factors... designing what will work, for you... I don't mean to dampen your enthusiasm, just somethings to think about.
Check YouTube and Instructables for project ideas.
JuculianD:
I have taken a look in the internet and found many useful ideas. I have a full concept now and do know which components to use. I do also know that the mechanical system will work. Obviously I will have to engineer as soon as I am have the parts to make it marine-proof. But that I will do that with my father.
Now, I am doing my electronics. I have found an open source project on github for a MPPT circuit with 32bit processor that is suitable for my project. I am now trying to get used to KiCad :phew: :palm:.
It is a great software but I am used to easyeda. I can not get my components imported as I can with LCSC + EasyEDA. Any ideas on that? Just take a diode with a similar footprint and change the name to the one I am using?
As soon as I have made progress I will let you take a look ;)
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